1. Field
Embodiments relate to an aromatic ring-containing polymer for a resist underlayer, a resist underlayer composition including same, and a method of patterning a device using the same.
2. Description of the Related Art
There is a continuous demand for reducing the size of structural shapes in the microelectronics industry and other related industries, including the manufacture of microscopic structures (e.g., micromachines and magneto-resist heads). In the microelectronics industry, there is a need for reducing the size of microelectronic devices in order to provide a number of circuits in a given chip size. Effective lithographic techniques are essential to achieve a reduction in the size of structural shapes.
A typical lithographic process involves the following processes. First, a resist is coated on an underlying material, and it is subjected to exposure to irradiation to form a resist layer. Thereafter, the resist layer is subjected to development using a developing solution to provide a patterned resist layer, and the underlying material exposed by the patterned resist layer is etched to transfer a pattern into the underlying material. After completion of the transfer, remaining portions of the resist layer are removed.
However, the resist may not provide resistance to the etching step to an extent that is sufficient to effectively transfer the desired pattern to an underlying material. In the case where an extremely thin resist layer is required, an underlying material to be etched is thick, a large etching depth is needed, or the use of a particular etchant is required depending on the type of underlying material, a resist underlayer may be used.
The resist underlayer acts as an intermediate layer (between the resist layer and the underlying material) that can be patterned by transfer from the patterned resist. The resist underlayer should be able to receive the pattern from the patterned resist layer and withstand etching required to transfer the pattern to the underlying material.
Many materials for such an underlayer have been suggested, but there is a need for improved underlayer compositions. Since conventional underlayer materials are difficult to apply to substrates, the use of chemical and physical vapor deposition, special solvents, and/or high-temperature baking may be required. However, these methods have a high cost.
Thus, an underlayer composition that can be applied by spin-coating techniques without high temperature baking has been recently researched. An underlayer that can be selectively etched using an overlying resist layer as a mask in an easy manner, while being resistant to etching necessary to pattern an underlying metal layer using the underlayer as a mask, also needs to be researched.
An underlayer composition that provides desirable storage life-span properties and avoids unwanted interactions (e.g., resist or substrate pollution caused by acid catalyst in the underlayer composition a hard mask) with an imaging resist layer also needs to be researched. An underlayer composition that has predetermined optical properties against imaging irradiation of short wavelengths (e.g., 157 nm, 193 nm, and 248 nm) also needs to be researched.
In summary, an antireflective underlayer having high etching selectivity and sufficient resistance against multiple etching, as well as minimized reflectivity between a resist and underlying material, is needed for lithography in order to enable production of a very fine semiconductor device.